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Kite rigs are wind-assisted propulsion systems for propelling a vehicle. They differ from conventional in that they are flown from kite control lines, not supported by masts.
Vehicles driven by kites include kiteboating, kite buggy, and vehicles with snowkiting and iceboating runners. They may be as simple as a person flying a kite while standing on a specialized skateboard, or be large, complex systems fixed to the vehicle, with powered and automated controls. They have recreational and commercial uses.
A power kite is held at an angle to the wind using control lines. Like any other sail, the kite develops lift and drag, pulling the vessel. The vector of the kite's pull is vector space produced by the vessel (water resistance against the hull, force of wheels against the ground, etc.) to move the vessel in the desired direction.
Windspeed increases with height, allowing kites to develop substantially more thrust per unit area than a conventional sail. Winds are also steadier and less turbulent higher up.
Kites may be adjusted with respect to the wind, manually or by an automated system. A kite cannot stay aloft when there is no wind, and must be re-launched.
The SkySails propulsion system consists of a large foil kite, an electronics control system for the kite, and an automatic system to retract the kite.
The kite, while 1–2 orders of magnitude larger, bears similarities to the used in kitesurfing. However, the kite is an inflatable rather than a ram-air kite. Additionally, a control pod is used rather than direct tension on multiple kite control lines; only one line runs the full distance from kite to ship, with the bridle lines running from kite to control pod. Power to the pod is provided by cables embedded in the line; the same line also carries commands to the control pod from the ship. Airborne Wind Energy Systems, a review of the technologies, A. cherubini, A. Papini, R. Vertechy, M.Fontana, Renewable and Sustainable Energy Reviews, 2015
The kite is launched and recovered by an animated mast or arm, which grips the kite by its leading edge. The mast also inflates and deflates the kite. When not in use, mast and deflated kite fold away.
Maartje Theadora, a large fishing trawler, was retrofitted with a kite rig in 2010.
Use
A commercial cargo ship, the MS Beluga Skysails, was built, and launched in 2007, with a kite rig supplementing conventional propulsion. A European Union-funded four-year study of wind propulsion, using the MS Beluga Skysails, reported that the ship attained 5% fuel savings overall, which translated into of CO2 for a typical year and itinerary. The study concluded that 25,000 similarly equipped ships could reduce fuel consumption by and save of CO2, of NOx. The return on investment for installing a kite sail was estimated to be about two-three years. On her maiden voyage, MS Beluga Skysails saved an estimated 10–15% fuel, $1,000 to $1,500 per day, while the kite was in use.
Companies
Skysails and KiteShip both made kite rigs.
See also
External links
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